Device for the feed of elastomer threads particularly in circular knitting machines

ABSTRACT

DEVICE ADAPTED FOR FEED OF ELASTOMER THREADS FROM A PLURALITY OF ROTATABLE BOBBINS, ESPECIALLY ADAPTED FOR CIRCULAR KNITTING MACHINES, CHARACTERIZED BY A COMMON BELT OR BAND BOBBIN-DRIVE MEANS AND BRAKING MEANS, WHICH ARE CONSTRUCTED AND COUPLED IN SUCH A WAY THAT IN   ROTATION OF THE BOBBINS THEY YIELD EQUAL CIRCUMFERENTIAL VELOCITIES OF THE ELASTOMER THREAD WINDINGS ON RESPECTIVE BOBBINS.

G. WURM DEVICE FOR THE FEED OF ELASTOMER THREADS, PARTICULARLY IN CIRCULAR KNITTING MACHINES Filed May 21, 1969 INVENTOR GUNTER WURM:

A K83, Lib/ALW- ATTOR NEYS United States Patent DEVICE FOR THE FEED 0F ELASTOMER THREADS, PARTICULARLY IN CIRCULAR KNITTING MACHINES Giinter Wurm, Wuppertal-Sudberg, Germany, asslgnor to Glanzstoff AG, Wuppertal, Germany Filed May 21, 1969, Ser. No. 826,324 Claims priority, application Germany, May 28, 1968, P 17 60 504.8 Int. Cl. D04b /50 US. Cl. 66-132 T 4 Claims ABSTRACT OF THE DISCLOSURE Device adapted for feed of elastomer threads from a plurality of rotatable bobbins, especially adapted for circular knitting machines, characterized by a common belt or band bobbin-drive means and braking means, which are constructed and coupled in such a way that in rotation of the bobbins they yield equal circumferential velocities of the elastomer thread windings on respective bobbins.

There exist known devices for the supplying of elastomer threads to circular knitting machines, in which the threads drawn off from the delivery bobbins pass over thread brakes into a delivery mechanism and thereupon into the knitting system. The thread brakes and delivery mechanism have the function of imparting to the thread a constant preliminary tension independently of the tension fluctuations imparted to the thread by its drawing-off from the bobbin. Through over-head draw-off of the clastomer thread from the delivery bobbin, stretchings of the thread can reach up to 70% of the maximum extension of such threads.

The above-mentioned devices operate faultlessly only if the elastomer thread receives a preliminary tension which generates a stretch of the thread of about 80% of the maximum stretch. With this stretch, the thread passes to the delivery mechanism proper.

In other known devices the preliminary tension is imparted to the elastomer thread drawn off from the delivery bobbin by other special control means before the thread runs into the delivery mechanism proper for the knitting system.

With the aid of these devices the elastomer thread can be supplied to the knitting system with any desired stretch, which is generated by the delivery mechanism. In these devices, however, the tension fluctuations in the elastomer thread disadvantageously are caught up by slack loops arranged between the delivery bobbin and deli /ery mechanism. The loops compensate for brief, relatively small tension fluctuations in the elastomer thread, but long-lasting and repeated tension fluctuations stretch the loop and are propagated up to the knitting system.

A further device is known in which the axial shaft of the delivery bobbin is connected in closed linkage with the drive of the delivery mechanism for the supplying of the elastomer threads into the knitting system. The elastomer thread is drawn off from the bobbin laterally, runs through two eyes and thereupon passes into the delivery mechanism. The drawback of this device lies in that the rotation speed of the delivery bobbin remains the same during the unwinding process as the diameter of the delivery bobbin decreases. Thereby the amount of thread conveyed per time unit fluctuates, so that the thread receives different preliminary tensions in dependence on the diameter of thread winding on the delivery bobbin.

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BRIEF DESCRIPTION OF THE INVENTION The primary object of this invention is to provide thread delivery mechanisms which avoid the disadvantages of the devices known hitherto and supplies elastic thread to a knitting system with predetermined, adjustable stretch of the elastic thread adapted to the requirements of the textile material produced. The bobbins are provided With drive and braking means which are constructed and coupled in such a way that the windings on each bobbin rotate with equal circumferential velocity.

In the case of delivery bobbins rotatably journalled very nearly without friction, from which the elastomer threads are drawn off under stretch, the means imparting equal circumferential velocity to the bobbins has a braking effect on the bobbins. If the delivery bobbins are braked by frictional forces, in which the threads are drawn off from the bobbins without stretch or with only slight stretch, then the means imparting equal circumferential velocity to the bobbins has a driving action on the bobbins. Where the circumferential velocity of the bobbins remains constant, the amount of thread running off laterally from the respective bobbins and thereafter over one or more deflection rollers to the knitting system per unit time, i.e., the respective linear velocity, is constant and independent of the diameter of the windings on respective delivery bobbins.

A preferred bobbin drive embodiment of the invention is one wherein the bobbins are arranged symmetrically in a circular pattern. These bobbins with their respective windings of elastomer threads are rotatably mounted on axial shafts which are perpendicular to the plane formed by the circular pattern, and a pulley-driven belt or an endless band interconnects the bobbins in such a way that a portion of the surface of each bobbin Winding is encircled by the belt or band.

The belt pulley for the drive ofthe belt or endless band is, in a preferred form, connected directly, e.g., by means of gears, with the drive of the knitting machine. In this manner there is a fixed relation between the amount of thread delivered per time unit and the thread draw-off requirements per time unit of the knitting system. The contact pressure of the band or belt against the bobbin winding surfaces is kept equal or approximately equal as the bobbin diameter decreases by use of a weight-loaded or spring-loaded pulley to maintain the belt or band tension.

In order not to damage the threads on the surface of the delivery bobbin, the drive force via frictional engagement between the belt or pulley and the respective Windings must be uniformly distributed over a substantial surface. A very favorable force transmission is obtained by an arrangement such that the belt or band encircles the winding surface over an are which is equal to or greater than 10% of the circumference of the respective windings on the delivery bobbins. .This condition is fulfilled in the device according to the invention by deflection pulleys interposed between the delivery bobbins, over which pulleys the belt or the band is guided in an undulating path.

The deflection pulleys simultaneously serve tohold the belt or band in a constant vertical position. The position of the belt or band on the surface of the delivery bobbin can be adapted, according to the invention, to the particular conditions or to the various bobbin forms, by mounting the deflection pulleys on axial shafts which are parallel to the bobbin axes and are adjustably mounted in the axial direction.

Depending on the type of goods produced on the knitting machine it is frequently required that the stretch of the elastomer thread during feed from the bobbins be varied according to program. The latter may be achieved by the setting of the speed of the belt or band adapted to the particular conditions. In a preferred form for this purpose, the belt-drive pulley is connected with a drive having a programmed adjustable rotational output. In the event that a change of the band or belt speed is not required during a knitting operation, the requisite stretch for the various goods produced on the knitting machine preferably can be adjusted by the means of a variable diameter belt-driving pulley, e.g., a frustoconical pulley. The number of delivery bobbins driven by the belt is arbitrarily variable up to the maximum number of delivery bobbins. The above-mentioned device is especially advantageous with use of a plurality of delivery bobbins, but also has the advantages mentioned over the known devices even in the case of the use of only one delivery bobbin.

DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention is illustrated in the drawing, wherein:

FIG. 1 is a schematic plan view thereof;

FIG. 2 is a side elevation of a delivery bobbin and the elements for feed of the thread to the knitting system; and

FIG. 3 is a front elevation of a delivery bobbin and its belt drive.

DESCRIPTION OF THE PREFERRED EMBODIMENT The delivery bobbins 1 for the elastomer threads 2 are arranged in a circular pattern on a frame 4. Each bobbin 1 is rotatably journalled on an axial shaft 3, which is mounted on the frame 4. The frame 4 is mounted on a knitting machine.

The windings 1a of the bobbins 1 are encircled on a portion of their surface 5 by the belt 6. The encircling arc 7 depends on the position and the diameter of the deflection pulleys 8 interposed between the respective delivery bobbins 1. The tension pulley 10 in a housing 10a biased by the spring 9, or with a weight if desired, keeps the belt 6 under approximately uniform. tension, independently of the diameter and the number of delivery bobbins 1 or of the diameter of the belt-drive pulley 11. The belt-driving-diameter of the belt-drive pulley 11 is adjustable by virtue of its frusto-conical shape. The axial shaft 12 of the belt pulley 11 is connected by means of gears or other direct drive with the main drive for the knitting system 13 :(not shown in detail). The elastomer threads 2 run laterally off from the delivery bobbins 1 and pass over the deflection rollers 14 and 15 into the knitting system 13.

The deflection pulleys 8 are provided with flanges to maintain a constant path of the belt 6 over the circumferences 5 of the delivery bobbins 1. These pulleys 8 respectively are journalled rotatably on vertical shafts 16, which are carried by the frame 4. The axial shafts 16 are adjustable in axial direction and are maintained 4 in their set height by attachment of said shafts to the frame 4 by the nuts 17.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. Apparatus adapted for feed of elastomer threads from a plurality of bobbins in a circular knitting machine which comprises a frame, a plurality of bobbins rotatably mounted on said frame about vertical axes of rotation in a circular pattern on said frame, and common drive and braking means correlated with the drive of the knitting machine coupling said bobbins to provide equal circumferential velocities of elastomer thread windings as the threads are drawn off respective windings, said drive and braking means being a driven endless belt interconnecting said bobbins, a plurality of belt-deflection pulleys with vertical axes of rotation interposed between respective bobbins, said belt being guided in an undulating path across said pulleys and the circumference of respective windings on each bobbin with said belt contacting at least 10% of the circumference of a Winding on each bobbin and driving and braking each bobbin and its windings by frictional engagement therewith.

2. Apparatus as claimed in claim 1 wherein said endless belt is driven by a pulley in direct drive with the main drive of the knitting machine.

3. Apparatus as claimed in claim 1 wherein said deflection pulleys are rotatably journalled on vertical shafts parallel to the bobbin axes, and means for axially adjusting the respective positions of said shafts.

4. Apparatus as claimed in claim 1, and a drivediameter-adjustable pulley driving said belt.

References Cited UNITED STATES PATENTS 2,290,628 7/1942 Alderfer 66l32 2,306,660 12/1942 Gift, Jr. 66l32 UX 2,441,189 5/1948 Eshleman 66l32 X 3,243,091 3/1966 Rosen 66132 T X 3,303,671 2/1967 Oliver 66l32 FOREIGN PATENTS 1,109,788 4/1968 Great Britain 66l32 1,050,510 12/1966 Great Britain 66132 T 1,067,038 4/1967 Great Britain 66132 T ROBERT R. MACKEY, Primary Examiner US. Cl. X.R. 66125 R 

